The 16-35 II is already 82mm. Why on earth would they make it smaller when 82mm is turning into the new standard for the zooms? The 24-70 II is 82mm, and surely the 70-200 III (if ever made) would avail itself of that added surface area.

Eventually, I think 77mm filters will be relegated to 'one-step-down-from-priciest' L lenses, like the 17-40, 24-105, 24-70 F/4, etc.

I hope not. The 70-200mm f/2.8L IS II USM is already a big lens, I hope Canon wouldn't make it any larger.

As far as I understand, the wide lenses got a larger wide element to help reduce vignetting, which is redundant on long lenses.

Fair, but why on earth are the front elements of the white superteles so big? It's not just because they are rear-filtered. Surely, being able to pull in more light must contribute to the IQ in a positive way, right? Otherwise, why would they do it?

A weather-sealed 16-50mm f/4 IS sounds wonderful. As does the 14-24mm f/2.8 - but what'll she cost? $3K?

As a 16-35mm f/2.8 L III ...

with 77mm filter threads and IS please...

+1 to me a "16-50ish" F/4 IS with 77mm threads and IS would be very attractive, and would fit nicely into the current lineup without tromping on the 16-35 f/2.8 II which appears is here to stay. Sure f/2.8 would be nice but thats the job for a 16-35 III, imho. If such a lens really materializes with that long of a maximum FL, IS will be important even for candids, not to mention narrow aperture landscapes in a pinch where you don't have a tripod. I've even obtained some resonable results with handheld HDR -- with 6fps and a fast enough minimum shutter speed.

I see IS going on everything eventually. It's useful at any FL in low-light handheld conditions and videographers always seem to want it. Plus it's a chance for Canon to refresh and upcharge an existing lens design.

Further, it's so much easier (and lighter!) than making lenses a stop faster. One might imagine standard lenses of the future all being F/4 or F/2.8 with 6-7 stops of IS. :-P

The 16-35 II is already 82mm. Why on earth would they make it smaller when 82mm is turning into the new standard for the zooms? The 24-70 II is 82mm, and surely the 70-200 III (if ever made) would avail itself of that added surface area.

Eventually, I think 77mm filters will be relegated to 'one-step-down-from-priciest' L lenses, like the 17-40, 24-105, 24-70 F/4, etc.

I hope not. The 70-200mm f/2.8L IS II USM is already a big lens, I hope Canon wouldn't make it any larger.

As far as I understand, the wide lenses got a larger wide element to help reduce vignetting, which is redundant on long lenses.

Fair, but why on earth are the front elements of the white superteles so big? It's not just because they are rear-filtered. Surely, being able to pull in more light must contribute to the IQ in a positive way, right? Otherwise, why would they do it?

- A

The larger the diameter the faster the lens. In fact Diameter = (Focal Length) / Aperture.

The larger the diameter the faster the lens. In fact Diameter = (Focal Length) / Aperture.

But still some lenses have a larger front than would be absolutely essential (example: 100L/2.8 @67mm & 100 non-L @58mm).

A larger diameter might be required for a) the addition if IS, b) afaik it also results in a better bokeh and c) sometimes it's absolutely unecessary like with the 17-40L that could be smaller but is built to accept the "standard" 77mm filter size.

The larger the diameter the faster the lens. In fact Diameter = (Focal Length) / Aperture.

But still some lenses have a larger front than would be absolutely essential (example: 100L/2.8 @67mm & 100 non-L @58mm).

A larger diameter might be required for a) the addition if IS, b) afaik it also results in a better bokeh and c) sometimes it's absolutely unecessary like with the 17-40L that could be smaller but is built to accept the "standard" 77mm filter size.

Indeed, my Zeiss 21mm and my Canon TS-E 24mm II use 82mm filters but I guess this comes down to specific lens design. The question I answered however, was about the big white telephotos...

The larger the diameter the faster the lens. In fact Diameter = (Focal Length) / Aperture.

But still some lenses have a larger front than would be absolutely essential (example: 100L/2.8 @67mm & 100 non-L @58mm).

A larger diameter might be required for a) the addition if IS, b) afaik it also results in a better bokeh and c) sometimes it's absolutely unecessary like with the 17-40L that could be smaller but is built to accept the "standard" 77mm filter size.

Indeed, my Zeiss 21mm and my Canon TS-E 24mm II use 82mm filters but I guess this comes down to specific lens design. The question I answered however, was about the big white telephotos...

The aperture is the diameter of the iris opening inside the lens. This is equal to or smaller than the front element of the lens. The filter size is larger than the front element and the diameter of the lens is necessarily going to be wider to accommodate electronics and gearing for focusing and zooming etc...

e.g. 50m f/1.4 has an aperture of (50/1.4) = 35.7mm. The front element only slightly larger. The filter size is 58mm and the lens diameter is 73.7mm.

No, don't confuse aperture with apparent aperture. The opening inside the lens, the actual gap in the aperture blades, can be much smaller, or bigger, than the apparent aperture. The apparent aperture is the one that determines lens speed and it is determined by its actual size and the magnification of that size by the lens elements. Look at this diagram of a Canon supertelephoto, the red arrow is the aperture mechanism and as you can see it is much much smaller than the front element. But look at the lens from the front and the apparent aperture will be the size of the front element.

Too often we lose sight of the fact that photography is about capturing light, if we have the ability to take control of that light then we grow exponentially as photographers. More often than not the image is not about lens speed, sensor size, DR, MP's or AF, it is about the light.

No, don't confuse aperture with apparent aperture. The opening inside the lens, the actual gap in the aperture blades, can be much smaller, or bigger, than the apparent aperture.

Thanks, I didn't know the "apparent aperture" term - but I read about the aperture size being independent to the f-stop on zoom lenses. When is the actual aperture *larger* than the apparent aperture - uwa lenses? Or has the relation apparent-real aperture nothing to do with the focal length and just relates to the lens' general design?

No, don't confuse aperture with apparent aperture. The opening inside the lens, the actual gap in the aperture blades, can be much smaller, or bigger, than the apparent aperture.

Thanks, I didn't know the "apparent aperture" term - but I read about the aperture size being independent to the f-stop on zoom lenses. When is the actual aperture *larger* than the apparent aperture - uwa lenses? Or has the relation apparent-real aperture nothing to do with the focal length and just relates to the lens' general design?

The f stop value of a lens is defined by the focal length of the lens divided by the diameter of the objective lens (front element). so a 300mm lens with a 100mm front element has an f stop value of f2.8. That's how it works.But in recent years, lens designers have over sized the front element to reduce vignetting. But the theoretical f stop value should change. T stop values are more accurate and based on actual light transmission through the lens. Ever noticed that wide aperture primes tend to under expose by a 1/3 stop when shot wide open? Often it's the difference between the F stop value and T stop value.

No, don't confuse aperture with apparent aperture. The opening inside the lens, the actual gap in the aperture blades, can be much smaller, or bigger, than the apparent aperture. The apparent aperture is the one that determines lens speed and it is determined by its actual size and the magnification of that size by the lens elements. Look at this diagram of a Canon supertelephoto, the red arrow is the aperture mechanism and as you can see it is much much smaller than the front element. But look at the lens from the front and the apparent aperture will be the size of the front element.

It states that "the aperture of an optical system is the opening that determines the cone angle of a bundle of rays that come to a focus in the image plane"

I know that Wikipedia articles are community-driven so accuracy of the information might not be 100%, so by all means go ahead and modify it since you know that the information as represented is incorrect/incomplete/inaccurate.

When is the actual aperture *larger* than the apparent aperture - uwa lenses?

I was just covering my butt! I suspect there are some unusual designs of lenses where this is true, but even looking at my 17TS-E, far and away the most extreme lens I own, it honours the apparent aperture "rule".

The f stop value of a lens is defined by the focal length of the lens divided by the diameter of the objective lens (front element). so a 300mm lens with a 100mm front element has an f stop value of f2.8. That's how it works.

Basically it is, for simple lens designs like telephotos, but take my 17TS-E, it should have a 68mm front element, I can't measure it to be any more than 64-65mm.

Ever noticed that wide aperture primes tend to under expose by a 1/3 stop when shot wide open? Often it's the difference between the F stop value and T stop value.

Not with TTL metering systems, the underexposure is due to uncollimated light hitting the sensor at angles it can't fully record, which is why it is worse the further off axis, vignetting. This wasn't as big a problem with film as it will expose to light from any direction, but there is so much stuff in front of the sensor that effectively blocks light that isn't nicely aligned; the metering is carried out in the pentaprism and is not affected by this phenomena. The entire point of TTL metering is to take into account all light loss due to lens extension, transmission values etc, the metering works out the exposure based on the light it is receiving, not the aperture value set and ignoring the T-stop or effective f-stop.

It states that "the aperture of an optical system is the opening that determines the cone angle of a bundle of rays that come to a focus in the image plane"

I know that Wikipedia articles are community-driven so accuracy of the information might not be 100%, so by all means go ahead and modify it since you know that the information as represented is incorrect/incomplete/inaccurate.

On the occasions I have edited Wikipedia it has been unedited by the people who got it wrong in the first place, so I don't bother.

"In some contexts, especially in photography and astronomy, aperture refers to the diameter of the aperture stop rather than the physical stop or the opening itself. For example, in a telescope the aperture stop is typically the edges of the objective lens or mirror (or of the mount that holds it). One then speaks of a telescope as having, for example, a 100 centimeter aperture. Note that the aperture stop is not necessarily the smallest stop in the system. Magnification and demagnification by lenses and other elements can cause a relatively large stop to be the aperture stop for the system."

Hope it helps.

Logged

Too often we lose sight of the fact that photography is about capturing light, if we have the ability to take control of that light then we grow exponentially as photographers. More often than not the image is not about lens speed, sensor size, DR, MP's or AF, it is about the light.

"In some contexts, especially in photography and astronomy, aperture refers to the diameter of the aperture stop rather than the physical stop or the opening itself. For example, in a telescope the aperture stop is typically the edges of the objective lens or mirror (or of the mount that holds it). One then speaks of a telescope as having, for example, a 100 centimeter aperture. Note that the aperture stop is not necessarily the smallest stop in the system. Magnification and demagnification by lenses and other elements can cause a relatively large stop to be the aperture stop for the system."

I got tired of waiting for an announcement and bought the Rokinon 14mm f/2.8.

Sorry Canon, maybe you can pull it together by the time I decide to get a new 50mm.

What kind of lens is it supposed to replace? If you wanted a 14mm Canon already has one.If you wanted a new UWA zoom then the Rokinon 14mm clearly isn't.

Point taken, but unless you have unlimited funds, a lot of thought goes into buying a lens. I really wanted a new UWA lens. I've been anxiously awaiting word of what Canon might have to offer. A 16-50mm f/4 IS with 77 mm filter threads would have been a perfect fit for me. I'd heard it was one of the possibilities and have been waiting for an announcement to confirm or put it to rest for 9 months. Back in June the report was that they would announce within 6-8 months.

In any case, I got tired of waiting and bought the Rokinon. If it turns out that I like that lens and decide I don't need anything between 14mm and 24mm, Canon won't get my money for a new UWA. Incidentally, if they keep dragging their feet with their announcements, I'll probably get Sigma's 50mm too.